1. Field of the Invention
The present invention relates to a laminate. More particularly, it pertains to a laminate excellent in heat resistance, moisture resistance, hydrolytic resistance, tearability, dead foldability and gloss.
2. Description of the Related Arts
There has heretofore been used a laminate comprising a paper and resin as packaging material, release paper for industrial use, ovenable tray, baking carton and the like. Specifical examples of known laminates include a laminate of paper/polyethylene aimed at moisture resistance and heat sealing property, that of paper/polypropylene aimed at oil and chemical resistances and flexibility, that of paper/vinylidene chloride aimed at steam and gas barrier properties, that of paper/cellophane aimed at dead foldability, tearability and gloss, and those of paper/polymethylpentene and paper/polyester each aimed at heat resistance and the like.
In recent years, however, new demands have become greater in addition to the above-mentioned last two items of aims. More specifically, the paper/cellophane laminate is required to solve such problems as the use of a large amount of harmful chemicals during the production of cellophane films, complicated production process thereof by the remarkable variation in physical properties due to the moisture of the film to be obtained and expensive cost of the laminate. The paper/polymethylpentene laminate and paper/polyester laminate each aimed at heat resistance are incapable of enduring the cooking with the latest ovens; the paper/polyester laminate is liable to be hydrolyzed; and the paper/polymer laminate excluding paper/cellophane laminate involves the problem of insufficient dead foldability, that is, the failure to leave dead fold when folded. The solution of the foregoing problems is eagerly desired.
In view of the above-described situations, intensive research and investigation were made by the present inventors on the lamination of a paper and a variety of resins for the purpose of developing a laminate excellent not only in heat resistance, moisture resistance, water resistance and gloss but also in tearability and dead foldability. As a result, it has been discovered that the laminate of a styrenic polymer having a specific configuration and paper combined with each other meets all of the aforestated purposes. The present invention has been accomplished on the basis of the above-mentioned finding and information.